1. Field of the Invention
The present invention relates to single photon detectors using superconducting transmission lines.
2. Discussion of Related Art
Single photon detectors are used in Picosecond Imaging Circuit Analysis (“PICA”) for non-invasive diagnostics of semiconductors circuits. The photons emitted during the switching of Metal Oxide Semiconductor Field Effect Transistors (“MOSFET”) are detected and the information about their arrival time and source locations is recorded by computer. This information can be used to reconstruct the switching activity of a circuit and to make conclusions about the circuit's operation.
In the current marketplace there are quite a few single photon detectors, such as Photomultiplier Tubes (“PMT”), Multichannel Plate Photomultipliers (“MCP”), and Single Photon Avalanche Photodiodes (“SPAD”). They differ based on characteristics such as quantum efficiency, counting rate, time resolution, dark counting rate, spectral sensitivity capability, and imaging capability (spatial resolution of a detected photon).
An ideal single photon detector would have high quantum efficiency, high counting rate, high time resolution, low dark counting rate, high spectral sensitivity, and high spatial resolution. None of the existing single photon detectors satisfy these criteria. For example, the MCP provides imaging capabilities but it is slow (hundreds of picoseconds). SPAD (tens of picoseconds) is faster than MCP but lacks the imaging capabilities of MCP. Therefore a need exists for a fast imaging single photon detector.